Under preferences in BrightAuthor you can choose different languages on the clock tab. However this does not have any effect when I publish the presentation, which ever language I choose, it's still the English time format and English names for weekdays and months. The only way I can get any other language is to manually change all names in the customize window when it is set to English.
I'm currently using BrightAuthor 3.7.0.12 (but the result was the same in previous versions) and publishing to a HD210 with firmware 3.10.40.